Centrifugal casting machine



P. E. LORANG CENTRIFUGAL CASTING MACHINE Dec. 31, 1968 Sheet of Filed Feb. 16, 1967 \||ll| Illllllllllllllllidl flezz Q, Epica M4 am? N 6- De 31, 1958 P. E. L oRANG 3,419,066

CENTRIFUGAL CASTING MACHINE Filed Feb. 16, 1967 Sheet 2 of 2 21 d J9 Y 2o IL Y f dna @"l United States Patent O 3,419,066 CENTRIFUGAL CASTING MACHINE Pierre Edouard Lorang, Nancy, France, assigner to Centre de Recherches de Pont-A-Mousson, a French body corporate Filed Feb. 16, 1967, Ser. No. 616,614 Claims priority, application France, Mar. 10, 1966, 52,824 6 Claims. (Cl. 164-154) ABSTRACT F THE DISCLOSURE Centrifugal casting machine comprising an extractor for extracting the cast pipe from the mould and a control device automatically controlling operation of the extractor, the control device comprising photoelectric cell means responsive to the presence of one pipe end in the mould and to the extraction of the other pipe end. If the extractor fails to extract the pipe, the photoelectric means cause the extractor to make further attempts at extraction. If the pipe breaks inside the mould the photoelectric means stop operation of the extractor to enable a manually-controlled extraction of the remaining piece of pipe.

The present invention relates to centrifugal casting machines for casting pipes having a socket in accordance with the de Lavaud method, said machines having a cooled metal shell or mould, pouring trough and movable extractor, and more particularly to an automatic control device for these machines which strips and withdraws the pipes.

Machines of this type are already known in which the stripping device, termed extractor, is a carriage carrying an automatic tongs. The carriage approaches the end end of the centrifugal casting mould and the to-ngs grips the inside of the socket of the pipe which is still in the mould and, as the carriage moves rearwardly, the tongs extracts the pipe from the shell. In an automatic version this extractor can be brought into action by a contactor actuated by the machine at the required moment, that is, at the end of the centrifugal casting. If no extraction occurs, that is, if the tongs grips the pipe in an unsatisfactory manner so that the pipe remains inside the mould, it is necessary to return the extractor towards the pipe for a further attempt at extraction. This requires an attentive supervision and the continual presence of an operator. Further, human intervention stopping the automatic operational cycle slows down the rate of production.

The object of the present invention is to provide a centrifugal casting machine of the aforementioned type which is so improved as to avoid the necessity of human supervision owing to a stoppage of the automatic cycle without delay in the event of an imperfect extraction and, if need be, an automatic return of the extractor to the pipe gripping position so as to recommence the stripping operation. Thus, in the event of fail-ure of the extraction a first time, the loss of time is small.

The centrifugal casting machine according to the invention has a device electrically controlling the jack shifting the extractor, an electrovalve and relay automatically operating the extractor and is so arranged that the control device comprises two contactors placed respectively at the forward point of the travel of the extractor and at a short distance from said forward point, and in combination with the contactors: a photoelectric cell secured to the mould-carrying carriage at the pipe socket end of the mould, said photo-electric cell being oriented in such manner as to be responsive to the exit of the socket of the pipe at the moment of extraction, a second photoelectric cell capable of being eclipsed and mounted on the 3,419,066 Patented Dec. 31, 1968 carriage at the end thereof corresponding to the smooth male end of the pipe and so oriented as to be pointed at said male end inside the mould, the distance between said two photo-electric cells being slightly greater than the total length of the centrifugal casting mould and of the pipe to be cast and said two photo-electric cells being respectively responsive to the radiation of the molten iron and to the iron in the course of solidification.

The second cell is eclipsable so as not to be responsive to the radiation of the iron contained in the pouring trough. It can be withdrawable or combined with a withdrawable screen.

Further features and advantages of the invention will be apparent from the ensuing description with reference to the accompanying drawings.

In the drawings:

FIG. 1 is a diagrammatic assembly view of a centrifugal casting machine equipped with the electric control device according to the invention;

FIG. 2 is a partial diagrammatic elevational view of one end of the carriage carrying a retractable photo-electric cell, the latter being in its operative position;

FIG. 3 is a view similar to FIG. 2, the cell being in its retracted position;

FIG. 4 is the diagram of the principle of operation of the electric control device according to the invention;

FIG. 5 is a partial diagrammatic view corresponding to FIG. l of the machine in its position at the start of the withdrawal of a vcast pipe, and

FIG. 6 is a view similar to FIG. 5 of course of pipe withdrawal.

The illustrated embodiment concerns a casting machine of the de Lavaud type for centrifugally casting pipes. This machine comprises a tiltable casting ladle A which pours the molten metal into a pouring trough or passage B. The latter pours the metal into a shell or mould 1 carried by a carriage C which travels between points a and b of a runway which is slightly downwardly inclined from a to b. In the axial extension of the mould and of the runway ab is a movable extracting carriage E ca-rrying an automatic ton-gs P adapted to take hold of the cast pipe C inside the pipe socket so as to extract the pipe from the mould 1. The extractor E is movable on a runway which is also inclined between an upper point c and a lower point d. For this purpose, the extractor E is attached to a cable 2 which extends around pulleys 3 and around a pulley 4 carried at the end of the piston rod of a jack V so as to form .a pulley block arrangement. The ends of this pulley block arrangement are secured at points 5 and 6. This pulley block is of known type and enables a jack V whose travel is only half that of the extractor E to be employed.

Withdrawable supports 7 for the stripped pipe T are located above the runway c-d of the extractor E. They are withdrawn automatically to clear the extractor E at the required moment.

In accordance with the invention, the centrifugal casting machine is equipped with an electric control device for immediately detecting and defect in the extraction and remedying this defect.

This electric control device is constructed in the following manner:

The carriage C carries, at the pipe socket end of the mould 1, a rigidly mounted photoelectric cell which is so oriented as to be responsive to the exit of the socket of the pipe T being extracted (FIGS. 1, 5 and 6), and, at the pipe male or smooth end of the mould 1, a second retractable photoelectric cell 9 which is so oriented in its operative position as to be pointed at the interior of the end of the mould corresponding to the male end of the pipe to be cast.

the machine in The cells 8 and 9 are both responsive to the radiation of the molten iron and to the iron in course of solidilication. The retractable cell 9 is mounted at the end of a lever 10 which is mounted on the outside of the body of the carriage C to pivot about a pin 11. The lever 10 is shifted by a single-acting jack 12 having a return spring 13, for example through a mechanism comprising a rack 13a and a pinion 13b. It is swung into the operative position when the jack 12 is fed with fluid under pressure and retracted by the spring 13 as soon as the jack 12 is no longer fed.

As will be understood hereinafter, it is necessary to retract the photoelectric cell 9 during the pouring stage. The cell 9 is only swung to its operative position during the pipe-extracting stage.

The `iack 12 is actuated by an electrovalve under the control of a mechanical contact 14 mounted at the lower point b of the runway for the carriage C. The closure of the contact 14 by the carriage C at the lower point d of its travel swings the photoelectric cell 9 to the operative position of the latter.

A mechanical contact 15 placed on the runway c-d of the extractor E at a short distance from the upper point c gives the signal for the automatic return of the extractor E in the case of non-extraction or the immediate stoppage in the case of breakage of the pipe. The Contact 15 is actuated upon the passage of the extractor E and throughout the time of its presence between the position of the contact 15 and the upper point c of its travel, by a ramp D carried by the extractor E. It is released or unactuated for the rest of the time.

The electric control device (FIG. 4) comprises, broadly speaking, three circuits connected in parallel on a double wire network 16 supplying electrovalves controlling the jack V of the extractor E, namely a control circuit 17 for controlling the upward or forward travel of the extractor E from the point d to the point c and also the automatic return of the extractor E towards the carriage C subsequent to a non-extraction, that is, in the event that the pipe remains completely within the mould without being drawn along by the tongs P of the extractor; a control circuit 17a for controlling the downward or rearward travel of the extractor from the point c to the point d; a circuit 18 for maintaining the automatic extracting cycle, the opening of this circuit immediately stopping the automatic extracting cycle, in particular when the cast pipe T has broken inside the mould 1 and only a single piece is extracted, the remainder of the pipe remaining inside the mould.

Before considering the various circuits, note that there are associated with the cells 8 and 9 respectively amplifier relays 8a and 9a which respectively control switches A5, ASS and B9, B59. Switches C15 and D15 are associated with the contact 15.

In the circuit 17, the following are connected in series: an electrovalve EV controlling the forward and rearward travel of the extractor E, and the switch F of a contactor Cc corresponding to the end-of-travel of the extractor at the point c of its travel. The switches Ag and B9 of the amplifier relays 8a and 9a, which are respectively actuated by the photoelectric cells 8 and 9, and the switch C15 relay the mechanical contact 15. The switch A8 is closed at rest and opened when the cell S is actuated. The switch B9 is open at rest and closed when the cell 9 is actuated. The switch C15 and the Contact 26 of the contactor Cc are opened when they are actuated and remain closed at rest.

The electrovalve EV is also connected in series in the circuit 17a with the switch G of the double contactor Cc. When the contactor Cc is open at F in the circuit 17 it is closed at G in the circuit 17a and vice versa. A return spring 28 returns it to the closed position in the circuit 17. The double contactor Cc performs the function of a reversing switch for the electrovalve EV. When closed in the circuit 17, the contactor Cc controls this electrovalve for a direction of travel of the extractor towards the point c. When closed in the circuit 17a, the contactor controls the electrovalve for a direction of travel of the extractor towards the point d. The electrovalve is controlled in the known manner (not shown in the drawing) so that a pulse or momentary feed of the circuit 17 or the circuit 17a is suiiicient for causing the forward or rearward travel of the extractor E.

Mounted in the circuit 18 for maintaining the automatic cycle is a relay RA which allows the automatic extraction cycle. This relay RA controls an electric crcuit of known type (not shown) on which depends the automatic operation of the machine.

Following on the relay RA the circuit 18 is subdivided r into two parallel branches.

Mounted in one of the branches, 19, is a push-button 20 for the resumption of the automatic operation of the extractor after stoppage of the automatic cycle. Mounted in the other branch 21 of the circuit 18 is a switch Ha for the self feed of the relay RA. The push-button 20 and the switch Ha are combined with each other by an electric connection of known type, symbolically represented by a dot-dash line, so that pressure exerted on the push-button 20 closes the switch Ha and excites the relay RA, if the latter is open. In normal operation, the switch Ha is closed.

Following on the switch Ha, the branch 21 is divided into three parallel conductors 23, 24, 25 which are connected to the second wire of the feed circuit 16. Mounted in each of these conductors are respectively the switch A85, the switch B89 actuated by the cells 8 and 9, and the switch D15 controlled by the contact 15 in the same way as the switch C15 is closed. The passage of current in one of the three conductors connected in parallel 23, 24, 25 feeds the circuit 18. If the current no longer passes in any of the three conductors, the switch Ha opens and stops the relay RA which allows the automatic operation. The circuit 18 is then open.

The casting apparatus operates in the following manner:

It will be recalled that in the usual manner the carriage C carrying the mould 1 is shifted to the extreme upper or forward position a of its travel for pouring the iron in starting at the socket end of the pipe, that is, at the lower end of the mould 1. Then, the carriage C travels towards its extreme lower or rear point b so as to effect a good distribution of the iron over the whole of the mould 1. The casting therefore takes place during the travel of the carriage C from the point a to the point b. Following on this casting, with the carriage returned to the point b of its travel-and after several instants of stoppage to complete the centrifugal casting and allow the iron to cool and solidify-the extracting stage can start. The extractor E travels up to the forward or upper point c of its runway and introduces the tongs P into the socket of the cast pipe. The extractor E then travels rearwardly and extracts the cast pipe T. The stripped or extracted pipe T rests on the Withdrawable supports 7. After the extraction and discharge of the pipe T, the supports 7 are withdrawn. A new core is placed in the socket of the mould 1 and the cycle recommences.

The electric control device operates in the following manner:

(1) Normal extraction (FIGS. 5 and 6) At the end of the casting, when the carriage C has returned to the low point b of its travel, the contact 14 actuated by the carriage C controls the supply to the jack 12. The latter brings the cell 9 to the position in which it is pointed towards the interior of the mould at the pipe male end of the mould. The cell 9 is immediately excited or actuated since a pipe has just been cast and there is an infrared radiation from the male end of the pipe T. The switch B9 of the relay 9a controlled by the cell 9 is therefore closed in the circuit 17 controlling the forward travel of the extractor, whereas the switch BSg opens in the branch 24 of the circuit 18. On the other hand, the cell 8 is not actuated or excited. The switches A3 and ASS therefore remain closed- The switch C15 and the switch F of the contactor Cc are closed in the circuit 17 and the switch D15 open. Consequently:

(1) The circuit 17 controlling the forward travel of the extractor is closed (closure of the switches F of the contactor Cc, A8, B9 and C15).

(2) The circuit 18-21-23 for maintaining the automatic extracting cycle is closed (switches ASS and Ha closed).

The closure of the circuits 17 and 18-2123 allows the automatic forward travel of the extractor E towards the carriage C. This extractor travels towards the point c of its travel and actuates the contactor (opening of the switch C15 and closure of the switch D15). Notwithstanding the opening of the switch C15, the extractor continues to travel towards the point c since the electrovalve EV has recived a forward travel pulse. When it has arrived at the point c the extractor actuates the contactor Cc and thus opens the switch F of the contactor Cc in the circuit 17 and closes the switch D in the circuit 17a. Consequently:

(1) The circuit 17 is opened (opening at F).

(2) The circuit 17a controlling the rearward travel of the extractor is closed (closure at G).

(3) The circuit 18-21-23 for maintaining the automatic extracting cycle remains closed (switches Ha and ASS closed).

The automatic rearward and downward travel of the extractor E towards the lower point d of its travel is therefore automatically controlled. Notwithstanding the return of the contactor Cc to the position closing the circuit 17, the rearward travel of the extractor continues under the effect of the impulse given at the moment of arrival at point c. This effect only ceases upon arrival at point d.

When the extractor E extracts the pipe T from the mould in a normal manner (FIGS, 5-6), the cell 8 is excited or actuated by the exit of the stripped pipe T whereas the cell 9 is no longer actuated. The switches A11, B9 and ASB are therefore opened whereas the switch BSg is closed. Consequently:

(l) The circuit 17 is opened (opening of the switches A8 and B9).

(2) The circuit 18-21-24 for maintaining the automatic cycle is closed (switches Ha and BSS closed).

The extractor effects automatically its downward or rearward travel following the rearward travel control pulse given by the contactor Cc to the electrovalve EV and, in passing by the contact 15, releases it. Simultaneously, the switch C15 is closed and the switch D15 opened. The circuit 18-21-24 remains closed and therefore supplied with current. The circuit 17 remains open. When the extractor stops at the lower point d of its travel, the pipe T is completely extracted. The cells 8 and 9 are no longer actuated and the switches A8, ASB and BSg are closed, the switch B9 remaining open. Consequently:

(l) The circuit 17 controlling the forward and upward travel of the extractor remains open (opening of the switch B9).

(2) The circuit 17a controlling the rearward or downward travel of the extractor remains open.

(3) The circuits 18-21-23 (closure of the switch A83) and 18-21-24 (closure of the switch BSS) are closed.

The extractor E must wait before travelling forwardly until the cell 9 is actuated, that is to say, until the pipe has been completely cast.

(2) Non-extraction of a pipe Assume that the extractor is at its point c of its travel and that it starts to descend automatically under the con- 6 trol of the contactor Cc (circuit 17 open, circuits 17a and 18-21 closed).

In the event of non-extraction of the pipe, that is, when the extractor moves rearwardly from c to d without extracting pipe T, the tongs P having failed to grip the socket of the pipe, the cell 8 is not actuated whereas the cell 9 remains actuated. The switches A5, B9 and ASa are closed whereas the switch BSS is opened. In passing by the contact 15 the extractor E releases it (closure of the switch C15 and opening of the switch D15). Consequently:

1) The circuit 17 controlling the forward travel of the extractor is closed (closure of the switch F of the contactor Cc and of the switches A8, B9 and C15).

(2) The circuit 18-21-23 for maintaining the automatic cycle is closed (closure of the switches Ha and A58).

The automatic forward and upward travel of the extractor E is immediately brought about. The tongs P returns to a position for engaging in the socket ofthe cast pipe. If a second attempt at extracting succeeds, everything occurs as in the iirst case. Otherwise, a third attempt is automatically made.

(3) Fracture of a pipe inside the mould and the partial extraction of a piece of pipe Let it be assumed that the extractor is at the start of its travel from c towards d.

In this possible case, the cell 8 is actuated and the cell 9 is also actuated by the piece of pipe corresponding to the male end remaining in the mould. Under these conditions, the switches A11, ASB and BSS are opened. The switch B9 is closed. As soon as the extractor passes by the contact 15 and releases it, the switches C15 and D15 are opened. At this moment, the three branches 23, 24, 25 are opened. The circuit 18, 21 is opened. Consequently, the switch Ha is also opened and the relay RA of the circuit 18, 21 is no longer fed. The automatic operation is therefore stopped. Everything stops at the end of the travel of the extractor E to the point d. It is therefore necessary to extract manually the piece of pipe remaining in the mould. For example, an extension is mounted on the extractor E which permits gripping the piece remaining in the mould and the extractor is caused to move forwards and backwards by means of push-buttons (not shown). When the pieces of broken pipe have been removed, the cells 8 and 9 are no longer actuated. The switches A5, A811, BS9 are once more closed. The circuit 17 is opened (opening of the switch B9). The circuit 17a is opened by the opening of the switch G of the contator Ca. The circuits 18-21-23 and 18-21-24 still remain open( opening of the switch Ha).

It is necessary to depress the push-button 20 to close the switch Ha and consequently the circuit 18 and resume the automatic operation cycle. The relay RA is then once more fed. The automatic cycle can then recommence.

After the extraction of the pipe and the usual injection of ferrosilicon and mounting of the socket core, the carriage C of the mould moves towards the pouring trough B, releases the contact 14 which stops the supply to the jack 12 and retracts the cell 9 to the inoperative position.

Owing to the combination of the cells 8 and 9, supervision of the extraction of the pipe is automatic. In this way, it is possible to detect immediately any defect in the extraction without loss of time and without waiting until the extractor has travelled uselessly to the end of its travel at point d, but, on the contrary, as soon as the extractor, in moving rearwardly, reaches the contact 15 near the point c of its travel.

Owing to the combination of the cells 8 and 9 a correction of a defective extraction, that is, a return of the extractor to the point c can be effected automatically as soon as the extractor E depresses the contact 15 near the point c and consequently without loss of time. Owing to the retraction of the cell 9 during the casting stage, the automatic return of the extractor is not brought about in an untimely manner as would be the case if the photoelectric cell 9 were in the operative position when the iron flows through the pouring trough B.

Although a specific embodiment of the invention has been described, many modifications and changes may be made therein without departing from the scope of the invention as defined in the appended claims.

Thus, instead of providing a retractable cell 9 there could be provided a cell 9 which is fixed to the carriage C but provided with a retractable screen disposed in front of the cell. Said screen would be operated by a jack under the same conditions as the pivoting of the lever 10vr so as to mask the cell 9 during the casting stage and unmask it during the extracting stage.

Instead of being mounted above the axis of the outlet of the extracted pipe, the cell 8 could be mounted on the side of the machine and have a horizontal sighting line.

In addition to its function lmentioned hereinbefore, the Contact could change, in the known manner, the speed of the extractor E. The latter changes from a very low speed in the upper part of its travel, between the position of the contacter 15 and the point c, to a high speed between the position of the contactor 15 and the lower point d and vice versa.

Having now described my invention what I claim as new and desire to secure by Letters Patent is:

1. A centrifugal casting machine for casting a pipe having a socket end and a smooth male end, said machine comprising a mould carrying carriage, a mould on said carriage, a pouring trough, a pipe extractor movable between a rear point and a forward point, a jack for controlling the extractor and an electric control device for said jack having an electrovalve and a relay for automatic operation, said control device comprising, two contactors placed respectively at the forward point of the travel of the extractor and at a short distance from said forward point, and in combination with the contactors: a photoelectric cell secured to the mould-carrying carriage at the pipe socket end of the mould, said photoelectric cell being oriented in such manner as to be responsive to the exit of the socket of the pipe at the moment of extraction, a second photoelectric cell capable of being eclipsed and mounted on the carriage at the end thereof corresponding to the smooth male end of the pipe and so oriented as to be pointed at said male end inside the mould, the distance between said two photoelectric cells being slightly greater than the total length of the centrifugal casting mould and of the pipe to be cast and said two photoelectric cells being respectively responsive to the radiation of the molten iron and to the iron in the course of solidification.

2. AA centrifugal casting machine as claimed in claim 1, wherein the control device comprises, on one hand, two control circuits connected in parallel for controlling an electrovalve actuating the jack controlling the movements of the extractor in both directions, said two control circuits being connected to the electrovalve to control the electrovalve, each of said circuits corresponding to one direction of movement of the extractor and having in series relation a switch of a double contactor corresponding to the end of travel of the extractor in the forward direction, the circuit of the forward travel comprising furthermore in series relation two switches controlled by relays associated with the photoelectric cells and a switch controlled by the contactor located at a short distance from the forward point of the travel of the extractor and, on the other hand, a circuit which has in series relation a relay which authorizes the automatic operation and is subdivided into branches having in series switches controlled by the photoelectric cells; and a switch of the contactor located at a short distance from the forward point of the travel of the extractor.

3. A centrifugal casting machine as claimed in claim 1, wherein the photoelectric cell responsive to the exit of the socket of the pipe at the moment of extraction is fixed to the carriage carrying the mould and pointed toward the axis of the mould outside the latter.

4. A centrifugal casting machine as claimed in claim 1, wherein the cell capable of being eclipsed is retractable.

5. A centrifugal casting machine as claimed in claim 4, wherein said retractable photoelectric cell is mounted at the end of a pivotal lever which pivots the photoelectric cell to the operative and inoperative positions.

6. A centrifugal casting machine as claimed in claim 1, wherein said eclipsable photoelectric cell is combined with a movable screen and means for moving said screen between a position in which it masks the photoelectric cell and a position in which it is moved away from the photoelectric cell to allow the photoelectric cell to operate.

References Cited UNITED STATES PATENTS 9/1958 Beyer 164-295 X 7/1960 Szwed 164-l54 U.S. Cl. X.R. 164-286; Z50-222 

